Tarantula
Anatomy:

Tarantulas
like all spiders have an exoskeleton that is hard in some places yet
supple in others. The exoskeleton protects and encases the spiders internal
organs. Since this exoskeleton is hard unlike skin which stretches and
grows, the spider must moult or shed its skin in order to grow. Prior
to moulting your spider will refuse to eat for around one/two weeks,
this is normal and should be no cause for concern. Your spider will
spin a web like mat upon the substrate where it will then proceed to
turnover on its back. It may take several hours for your tarantula to
shed its skin completely and it may remain still for several hours after
whilst still remaining upside down, be aware that your spider is not
dead and this is normal. Do not poke or prod your spider during this
time, as disturbance could prove fatal.

DURING THE MOULTING PERIOD IT IS IMPORTANT NOT TO TOUCH OR
DISTURB YOUR SPIDER AS THIS IS THE TIME WHEN IT IS AT ITS MOST VULNERABLE,
AFTER MOULTING YOUR SPIDERS EXOSKELETON WILL BE EXTREMELY SOFT AND
IS PRONE TO DAMAGE. DO NOT FEED YOUR SPIDER FOR SEVERAL DAYS AS THE
INTRODUCTION OF INSECTS DURING THIS TIME COULD CAUSE INJURY TO YOUR
PET.

Unlike
insects, spiders have two main body parts instead of three. These are
the cephalothorax (head and thorax combined) at the front (anterior),
and the abdomen at the rear (posterior). They also have four pairs of
legs each of which has seven segments, and chelicerae instead of mandibles.
The chelicerae are to what the fangs are attached and also contain the
poison glands. The tarantula uses these to dig its burrow. Tarantulas
have vertically moving fangs, unlike most spiders which have horizontal
movement. The tarantula also has another pair of appendages as well
as its legs. These are the pedipalps, which are adjacent to the chelicerae
and look like short legs. The tarantula uses these to grab its prey
and also to move objects around. At the end of each leg tiny claws are
found which aid the spider and help it to cling when climbing.

The
cephalothorax is joined to the abdomen by thin narrow tissue known as
the pedicel. The top of the cephalothorax is known as the carapace on
which are mounted the eight eyes just behind the chelicerae raised inside
a small turret, the tarantula has four eyes for daytime vision and four
for night-time. Located inside the cephalothorax is the brain and also
the spiders sucking stomach. Within the abdomen are located the reproductive
organs and the heart. At the rear of the abdomen are found the spinnerets
used to produce silk. Tarantulas use silk to make their webs for many
different purposes. Arboreal (tree dwelling) tarantulas use silk to
make a nest in which they sit. Burrowing species may line their burrows
with it, wrap up their prey or eggs, and a tarantula will spin a bed
of silk in order to lie upon during moulting. Tarantulas unlike most
spiders have muscles which can independently control the movement of
the spinnerets. Underneath the spider located on the abdomen can be
seen the genital opening and also the four book lung slits. The spider
excretes waste via the anus found near the spinnerets.

Tarantulas have very small mouths. They eat their prey by firstly administering
venom which paralyses the prey and then slowly dissolves all of the
internal structure of the insect. The spider then proceeds to suck out
the dissolved solution until nothing is left except a small dehydrated
pellet of the insects outer skin.

Covering
the spiders whole body are hairs which are very sensitive to touch
and send signals to the brain via nerves. Tarantulas do not have ears
as such, however it has been suggested that some spiders may be able
to sense vibrations since some tarantulas do have the ability to produce
sound.